Today our topic of discussion is Thallium Testing.
Thallium Testing
THALLIUM TESTING
Thallium is a radioactive analog of potassium, which is readily taken up myocardial cells. After thallium 201 is given, almost 90% of it is extracted by the myocardium within seconds. For this to occur, two factors are essential: (adequate perfusion and (ii) Cellular extraction efficiency. Since cellular ischemia does not seem to affect thallium uptake in myocardium, its lack of uptake is an indication of an infraction (Fig. 29.107)
Purpose
- Thallium imaging is used to assess coronary blood flow to determine areas of infarction and ischemia
- To diagnose CAD and assess revascularization following coronary artery bypass surgery Thallium 201
- Thallium 201 is the most widely used isotope for myocardial perfusion due to its short (73 hours), half-life and low total body radiation dose
- Thallium 201 is a radioactive analogue of potassium, which is easily extracted by smooth skeletal and cardiac muscle fiber that possess the potassium active transport system
- A 80% of blood-borne thallium 201 is taken up on its first pass through the heart
- The amount of thallium 201 found in the myocardium after an intravenous injection depends on the regional myocardial perfusion and the efficiency of cellular extraction.
Client Preparation
- Ask female clients if they are pregnant or suspected pregnancy, because these studies involve radiation exposure
- Explain the purpose of the procedure to the client and tell him or what to expect during the procedure
- Explain that electrodes will be placed on the client and an intravenous line will be inserted for the administration of the radioisotope
- Generally, total exposure to radiation during these scan is less than or equal to that of one chest X-ray study .
- Instruct the client to wear walking shoes if exercise on the treadmill or bicycle is anticipated
- Encourage the client to notify the nurse or technologist of any signs of ischemia (chest pain) during or after the procedure
- Keep the client NPO for 4-6 hours before the test but may drink water
- An infusion is started for intravenous access Inform the client, of the need to go to the nuclear medicine department twice
- If a SPECT scan is planned, check if the client is claustrophobic.
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